Abstract: Based on the principle of energy dissipation, the damage characteristics of basalt fiber recycled concrete under freeze-thaw cycle are studied. The longitudinal wave velocity of freeze-thaw recycled concrete and basalt fiber recycled concrete is measured by non-metallic ultrasonic measuring instrument. The electro-hydraulic servo press and Hopkinson pressure bar device are used to carry out uniaxial compression tests on the specimens under static and dynamic loads. The changes of longitudinal wave velocity, relative dynamic elastic modulus and mechanical properties of the specimen are analyzed, with emphasis on the change law of energy dissipation. The results show that the freeze-thaw cycle will reduce the longitudinal wave velocity of the specimen, and the later freeze-thaw effect has a more obvious effect on the specimen. The addition of basalt fiber increases the integrity of recycled concrete and reduces the damage degree of freeze-thaw to the specimen. The strength and toughness of the specimen under dynamic load are higher than those under static load. The addition of basalt fiber increases the strength and ductility of recycled concrete. The peak stress and ductility of the specimen are continuously reduced by freezing and thawing, and the stress reduction degree is more obvious in the later stage of freezing and thawing. In the early stage of loading, the specimen will undergo elastic deformation, and the external input energy is stored in the form of elastic properties. The addition of basalt fiber can greatly improve the energy absorption effect of recycled concrete. The increase of freeze-thaw cycles reduces the energy consumption effect of the specimen and increases its mechanical damage. The freeze-thaw effect makes the specimen more prone to damage.

Key words: freeze thaw cycle, energy dissipation, basalt fiber, recycled concrete, toughness, relative dynamic modulus of elasticity, composites